In the working environment containing dust and poisonous gases, there have been conventionally known respiratory protection devices worn by an operator in order to prevent damage caused by the dust and the poisonous gases in the environment, and respiratory protection devices including a speaking diaphragm or a loudspeaker.
For example, a respiratory protection device disclosed by Japanese Unexamined Patent Application Publication No. 2003-117013A (Patent Literature 1) includes an electric fan unit on the bilateral side portion of a facepiece, and a speaking diaphragm is attached to the central portion in the width direction of the facepiece.
Also, a mask disclosed by Japanese Unexamined Utility Model Application Publication No. 1983-177151A (Patent Literature 2) includes a loudspeaker that facilitates conversation between operators. The loudspeaker includes a microphone, a speaker, a battery, and the others.